This invention generally relates to electrosurgery. More specifically, the invention relates to a new and improved electrosurgical generator and method that has the capability to detect malfunctions or errors in the delivery or distribution of high power electrosurgical energy to one or more electrosurgical instruments connected to the generator, thereby indicating and preventing malfunctions and error conditions which could possibly result in an unintended application of electrosurgical energy to a patient or to surgical personnel.
Electrosurgery involves applying relatively high voltage, radio frequency (RF) electrical energy to tissue of a patient undergoing surgery, for the purpose of cutting the tissue, coagulating or stopping blood or fluid flow from the tissue, or cutting and coagulating the tissue simultaneously. The high voltage, RF electrical energy is created by an electrosurgical generator, and the electrical energy from the generator is applied to the tissue from an instrument or handpiece manipulated by a surgeon during the surgical procedure.
In monopolar electrosurgery, the handpiece includes a single active electrode. The active electrode is applied to the tissue, and the electrical energy travels from the generator, through a conductor to the handpiece, from the active electrode of the handpiece into the tissue of the patient, where the cutting, coagulating or simultaneous cutting and coagulating effect is achieved at the interface of the active electrode with the tissue. The electrical current is distributed into the patient, collected from the patient by a return electrode connected to the patient at a location remote from the surgical site, and is returned to the electrosurgical generator by an electrical conductor connected to the return electrode.
In bipolar electrosurgery, the handpiece generally takes the form of a forceps. The active electrode and the return electrode are attached at opposite ends of the arms of the forceps. Tissue is grasped between the active and return electrodes and the electrosurgical energy is transferred directly between the active and return electrodes through the tissue. Bipolar electrosurgery is generally used only for coagulating tissue, such as by squeezing a severed vessel and applying the electrosurgical energy to seal the end of the severed vessel.
Frequently, a surgeon will use different monopolar and bipolar handpieces on an alternating basis during the course of the surgical procedure. For example, the surgeon may use a monopolar handpiece having a relatively straight active electrode for cutting, another monopolar handpiece having a different configuration of an active electrode for coagulating broad surfaces of oozing tissue, and bipolar forceps for coagulating blood flow from severed vessels. In some complex surgical procedures, two or more surgeons may perform a procedure on the same patient at the same time, but at different surgical sites. For example, in a heart bypass operation, one surgeon may be working at the thoracic cavity while another surgeon may be harvesting vessel tissue from a leg. In this situation, each surgeon will typically use a handpiece or handpieces separate from those used by the other surgeon.
In all of these situations, it is typical that the multiple handpieces are connected to a single electrosurgical generator. The surgeon controls the energy delivered to the selected handpiece by depressing a finger switch on the handpiece, or by stepping on a foot switch which is associated with the particular handpiece. Depressing a finger switch or stepping on a foot switch delivers an activation signal to the electrosurgical generator. The electrosurgical generator responds to the activation signal by delivering the electrosurgical energy to the handpiece with which the activation signal is associated. Most electrosurgical generators contain the capability of delivering monopolar electrosurgical energy to more than one connected handpiece, so relays are used to direct the high power electrosurgical energy only to the desired handpiece. Relays are used because the electrosurgical energy can be of high voltage, for example up to 10,000 volts, making it extremely difficult or impossible to use non-mechanical electrical switches for this purpose.
After many repeated openings and closures, an output relay of an electrosurgical generator can become worn, just like any other mechanical device which is subjected to repeated use. Sometimes a worn or defective output relay will not close when commanded to do so. In such circumstances, the electrosurgical energy will not be delivered to the handpiece and the surgeon quickly recognizes a malfunction of the electrosurgical generator. Sometimes a worn output relay will stick in the closed position. While an output relay that is stuck in the closed position may not be particularly problematic when only a single handpiece is connected to the electrosurgical generator, this is not the case when multiple handpieces are connected to the same generator.
An activation request for bipolar energy is interpreted by the electrosurgical generator to connect the necessary electrical components for delivering the electrosurgical energy directly to the bipolar forceps.
An output relay that is stuck in the closed position can deliver electrosurgical energy to its associated handpiece, even if that particular handpiece has not been selected by an activation request. The delivery of electrosurgical energy to an unintended handpiece can result in injury to the patient and to the surgical personnel. In some situations, the surgeon will lay the handpiece on the patient when the handpiece is not in use, simply because it is convenient to pick up the handpiece when the procedure requires the application of electrosurgical energy. In other cases, the surgeon may pass the handpiece to surgical support personnel who will hold the handpiece until the surgeon requires it, or the surgeon may hold or use the handpiece in a way that is safe so long as electrosurgical energy is not delivered from it. In all of these cases, if the active electrode of the handpiece becomes energized by a stuck output relay, there is a possibility of an unintended burn, injury or electrical shock to the patient, the surgeon or the surgical personnel. Moreover, there is also a possibility that an electrical short-circuit could be established through the generator, which would disable the generator and prevent its use for the remainder of the procedure. Under those circumstances, the procedure must be suspended while a replacement electrosurgical generator is located and brought into the operating room. Bipolar electrosurgical energy is typically delivered through different output electrical components from those that are connected in the output circuit of the electrosurgical generator when monopolar electrical energy is delivered. Because of the separate electrical delivery of bipolar ehectrosurgical energy, output relays may or may not be used to connect the bipolar electrosurgical energy to the bipolar handpieces. The misinterpretation of a bipolar activation request may erroneously deliver bipolar electrosurgical power to the bipolar handpiece.
In accordance with the improvements of the present invention, the operational condition and status of an output relay and the bipolar output delivery circuitry of an electrosurgical generator is detected and evaluated in response to activation requests. Evaluating the delivery of electrosurgical energy relative to expected conditions arising from the activation request detects a malfunction or error condition of an output relay or in the electrical components which deliver bipolar energy. Detecting a malfunction, and preventing the delivery of electrosurgical power under such conditions, avoids or minimizes the risk of unintentional injury, burns or electrical shock to the patient, the surgeon or the surgical personnel. The opportunity to assist in troubleshooting or identifying intermittently malfunctioning output relays or other internal malfunctions within the electrosurgical generator is also achieved from the present invention.
The invention involves a method of determining delivery conditions of output electrosurgical power from an electrosurgical generator. The electrosurgical power is delivered in response to an activation request for output power. A delivery path for the delivery of the electrosurgical power is selected based on the activation request. A determination is made whether the output power delivered is flowing in any delivery path other than the selected delivery path. The delivery of electrosurgical power is terminated upon determining that the delivered electrosurgical output power is flowing in a delivery path other than the selected delivery path. Preferably, a determination is also made whether the electrosurgical output power delivered is flowing in the selected delivery path, and the delivery of the electrosurgical power is terminated upon determining that output power is flowing in a delivery path other than the selected delivery path. The delivery path is preferably a selected one of a plurality of different delivery paths.
Another form of the invention involves delivering electrosurgical power in response to an activation request, commanding the delivery of electrosurgical power through a selected one of a plurality of delivery paths, sensing the flow of electrosurgical power in each of the plurality of delivery paths, determining whether the delivery path in which electrosurgical power is flowing correlates with the selected one delivery path and whether each delivery path in which electrosurgical power is not flowing correlates to a delivery path for which electrosurgical power delivery has not been commanded, and terminating the delivery of electrosurgical power if electrosurgical power is not flowing in the selected delivery path or if electrosurgical power is flowing in any delivery path other than the selected one delivery path.
The invention also involves an improved electrosurgical generator. The electrosurgical generator comprises a power creation circuit which is operative in response to an enable signal to create the output electrosurgical energy, a delivery path connected to the power creation circuit and through which the output electrosurgical energy is delivered, a selectively controllable power flow switch connected in the delivery path to conduct the electrosurgical energy through the delivery path in response to an assertion of a power command signal to the power flow switch and to prevent conduction of the electrosurgical power through the delivery path in response to the de-assertion of the power command signal, a controller receptive of an activation signal to the electrosurgical generator and operative to supply the enable signal to the power creation circuit and to assert the command signal to the power flow switch in response to the activation signal, a sensor connected to sense the flow of electrosurgical power through the delivery path and to assert a sense signal upon sensing the presence of electrosurgical energy flowing in the delivery path and to de-assert the sense signal upon sensing the absence of electrosurgical energy flowing in the delivery path, and a detection circuit receptive of the command signal and the sense signal and responsive to an inconsistency in one of the simultaneous assertions of the command and sense signals or the simultaneous de-assertion of the command and sense signals. The detection circuit terminates the enable signal to the power creation circuit upon detecting the inconsistency.
A more complete appreciation of the present disclosure and its scope, and the manner in which it achieves the above noted improvements, can be obtained by reference to the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings, which are briefly summarized below, and the appended claims.